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Therapeutic applications of light

12. Jun 2017

Research update.

Text: Anadi A. Martel

It is essential for professional lighting designers to understand that light, in addition to fulfilling the practical and aesthetic functions they are already familiar with, can also have a profound impact on our health and well-being. While light has traditionally been used for therapeutic purposes by most ancient cultures, since the beginning of the 21st century we are witnessing a remarkable acceleration in the amount of scientific research devoted to light medicine, with thousands of articles now published yearly. Lately there has been much talk in the lighting design community of “human-centric” aspects, such as melatonin suppression and blue light hazard. However, this is only the tip of the iceberg, with the surprisingly wide range of therapeutic applications of light going well beyond these topics. The purpose of this article is to provide a brief update on some of the latest research in the field, adapted to (and hopefully widening) the specific interests of lighting designers.

Light from the sun is the primary source of energy driving all life on our planet, so it is not surprising that it plays such a powerful role in human health. The use of light for healing is as old as humanity itself, and is documented in ancient Egyptian, Indian and Greek texts. Sunlight was a key medical tool for the ancients, either in its pure form as heliotherapy, or filtered through precious stones or other colored materials. In the West, its role was then obscured for many centuries because Christianity deemed heliotherapy to be a form of sun worship and proscribed it as paganism. Only towards the end of the 19th century did it begin to arouse renewed interest, with numerous heliotherapy centers throughout the world becoming the preferred medical providers for intractable diseases such as tuberculosis. Such was the respect accorded to light medicine during this period that one of the very first Nobel Prizes for Medicine was awarded to Nils Ryberg Finsen in 1903 for his pioneering work in phototherapy. Prize motivation: “in recognition of his contribution to the treatment of diseases, especially lupus vulgaris, with concentrated light radiation, whereby he has opened a new avenue for medical science”. This was not to last: with the rise of antibiotics in the 1930s light therapy was again relegated to “medical paganism”, this time through the war between orthodox medicine (pharmaceutical) and alternative medicine or therapies. There it remained for the remainder of the 20th century – until two key discoveries initiated the current renaissance in light medicine.

Light for the body: medical applications
The first discovery is that light can directly enhance cell metabolism, through a complex chain of biochemical processes termed photobiomodulation by the main researcher behind its discovery: Tiina Karu. Prof. Karu worked patiently on this field of light therapy throughout the 1980s and 1990s in her Moscow lab – even though she was not taken seriously at the beginning of her research. She identified mitochondria (tiny energy engines within each of our cells) as the main recipients of light stimulation, mostly driven by red and near-infrared (NIR) frequencies. This understanding opened up the whole new field of Low Level Laser Therapy (LLLT), where nonthermal low levels of light are used for various regenerative purposes. Riding on applications research conducted by NASA in the early 2000s, LLLT is now gaining widespread acceptance. The underlying photobiomodulation cellular processes involved are now the focus of intensive worldwide research, and the specific effects of different colors are being explored. For example, blue is used for acne treatment, yelloworange for skin toning, red for wound healing, infrared for joint relief.

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